Fitments
99-06 Twin Cam (excl. 2006 Dyna) with non-hydraulic chain tensioners (NU)
Part Description
S&S, gear drive 640G camshaft set (IG)
.640" valve lift. IG = gear drive cam set with installed Inner Gears only. The gear drive system is in fact a revolutionary different and much more reliable construction. Especially in high lift/performance applications, when compared with the OEM chain-drive design. A gear driven camshaft is stronger and will not give any of the mechanical problems connected with the OEM chain driven camshafts. The S&S gear drive kit will increase valve timing accuracy, and therefore horsepower, by eliminating the timing chain lash and loosely fit stock cam gears. The only downside of gear drive is that you may experience a slight increase in mechanical sound, this is why OEM is using a chain. It has no other mechanical advantages whatsoever. Since the chain guides and tensioner are eliminated there is no longer the possibility for these parts to fail and damage other engine parts. The S&S gear drive kit reverses the direction of rotation of the rear cam, providing additional operating clearance between cam lobes. As a result, higher cam lifts are possible with the S&S gear driven cams. Note: With the exception of the 475G and 510G cam, adjustable pushrods (like MCS 503573) are required to compensate for the smaller camshaft base circle of these cams. Note: An S&S gear drive installation support kit (MCS 503566) can be ordered separately if required. Kit includes a set of cam bearings, retaining ring and gasket. Note: Material may have to be removed from the inner surface of the OEM gear cover before installation of the S&S outer drive gears (which are required and available as 503577). Note: Using .625", .635", .640" and .675" lift cams will require crankcase clearancing. Note: OEM beehive valve springs of 04-17 Dyna; 04-17 Softail and 04-16 Touring models will acommodate valve lifts up to 590" valve lift and, 160 lb. of valve seat force, up to 6200RPM. Running higher than 6200 RPM or lifts greater than 590" will require performance valve springs.
